Stevek
off to a rocking start
Member since December 2004
Posts: 21
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Post by Stevek on Feb 25, 2005 11:50:03 GMT -5
I'm pretty new to tumbling. This forum has been a great source of information. I picked up a couple of used Thumlers dual 3 Pound tumblers off e-bay and have them running (I'm too impatient for only one rotary tumbler).
I noticed that one of the tumblers has the barrels tumbling at about a 50 percent higher rotational rate. This made me come up with a few questions I have not seen discussed here:
What is the best tumbling rate for the three pound barrels? (should I adjust one of mine?)
Should I do rough shaping on the faster tumbler and polishing on the slower one? Visa versa?
Should I switch the barrels on the two tumblers at mid week so they all tumble the same amount in total?
Your coments would be appreciated.
Steve -
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Post by Tweetiepy on Feb 25, 2005 12:18:13 GMT -5
I'm along the same line, I have a 33B and only one has rocks in it, but both are spinning, well the one with rock spins slower than the one without. Is this normal?
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Post by Cher on Feb 25, 2005 12:18:45 GMT -5
I don't know what the "best" speeds are but I have a CE that tumbles faster than my lortones. I always used this one for the coarse grit stage. Now that I have the QT66, it's used for 120/200 grit only, thinking faster is better. I know "rotations per minute" was discussed but that was quite awhile ago.
Anyway ... Welcome to the forum Steve, you've definitely found a great group of very helpful and generous people. Only thing I can add is you'll need to work on the "patience" if you want to get really nice shine. (Thinking 2 weeks in polish is so hard to do.)
Cher
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MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
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Post by MichiganRocks on Feb 25, 2005 12:30:55 GMT -5
The critical measure is linear speed. In order for the linear speed of all barrels to be the same, the larger diameter barrel must turn at a slower angular velocity (RPMs). So a small tumbler with small barrels will spin at a faster rate (higher RPMs) than a larger diameter barrel. I would think that most 3 lb. barrels probably run in the neighborhood of 50 RPM.
Ron
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Stevek
off to a rocking start
Member since December 2004
Posts: 21
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Post by Stevek on Feb 25, 2005 14:12:31 GMT -5
It might be helpful if we measure RPMs for different tumblers and compare. I didn't do a careful measure but from an approximate estimate I would think one of mine is running around 40-50 rpm and the other at around 70 rpm. I'll try to get a better measurement.
Cher - I understand your comment on "patience" and the results. Part of my reason for another tumbler is that I was keeping the rocks in the coarse grit for shaping for many weeks. I was collecting too many rocks and wanted to get them going. I also wanted additional barrels to perform the medium through polish stages while some rocks were in coarse.
I have been having trouble getting a quality shine on my rocks. I have several thoughts on the reason why - but I don't believe it is from not running long enough cycles. I'll probably start a new topic with my questions on this subject.
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Post by connrock on Feb 25, 2005 19:45:13 GMT -5
It's much better to rough fast and polish/burnish slow. I do 99% of my roughing in a Thumler's Model B at twice the speed of a normal unit. I also do some of my roughing in a Lortone 6 lb barrel.I wanted to speed it up but didn't want to have to change pullys because of the belt length factor. Instead I wound 1/4" diameter round rubber material around the drive roller and just taped it with duct tape.It really speeds things along and when I want the normal speed I just take the rubber off. Here's a chart on tumbling speeds. Suggested speeds for various sizes and types of drums in revolutions per minute are: Drum Diameter 4.5' 6" 8" 10" Hexagonal Drum 35 32 29 25 Round Drum 60 54 48 42 Tom
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Stevek
off to a rocking start
Member since December 2004
Posts: 21
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Post by Stevek on Feb 26, 2005 12:30:04 GMT -5
Thanks for the input, that is helpful. I took my watch to the garage and timed my two 3 lb Thumler tumblers. The fast one is about 58 rmp and the slow one is at 34 rpm.
I think for now I'll continue to use the fast one for rough and shaping. However, I think I need to make some adjustments to speed up the slower one.
Steve -
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Post by guest on Feb 27, 2005 3:42:47 GMT -5
The professional engineers with the tumbling companies have preset the best speeds---I suppose they get paid the "big bucks" to solve answer your question..
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Post by connrock on Feb 27, 2005 16:41:35 GMT -5
What our "guest" said is true but it's only a starting point as are all the basic tumbling instructions. They,(the manufacturers), have come up with these speeds and tumbling instructions using engineering methods for general use on the most common tumbling materials but are not tried and true to perform all aspects of tumbling which cover a wide variety of materials and their need of more refind methods. Tom
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earthdog
Cave Dweller
Don't eat yellow snow
Member since June 2006
Posts: 2,731
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Post by earthdog on Feb 28, 2005 13:25:56 GMT -5
Man, I have both of the C.E. tumblers,(single and dual) My dual runs at 25 r.p.min. and my single runs at 42 r.p.min. My stuff is slow! I'm in pre-polish now with the single and it's doing a good job. And I thought the dual was going an ok job with my 2nd grit stage.
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